hello... my puzzles which i solve are saved then when i open the 'my solved' section few days later , they are disappeared . please help cause i have solved many puzzles but my 'solved' doesn't show them

You are most likely playing the weekly free puzzles. These stay free for a week unless you purchase the puzzle (or weekly package). After a week, any free puzzles that are not purchased are reset to unsolved and the status changed to 'buy'.